SU779871A1 - Soil moisture-content sensor - Google Patents

Description

I

The invention relates to a measurement technique, namely, electrical devices for measuring humidity and can be used in agriculture and land reclamation.

There are continental humidity sensors,

one of the main parts of which is a pair of electrodes ll.

Sensors operate on the principle of change

interelectrode conductivity with changes in moisture material it. However, the interelectrode conductivity varies not only with changes in humidity, but also with changes, and temperature, salt concentration in the material., 5

Closest to the invention is a moisture sensor comprising a porous body filled with ion-containing. resin, which houses the electrodes G21., 20

The ion exchange salts show a buffering effect to a change in the salt concentration in the soil solution by decreasing the salt concentration in the interelectrode space due to the exchange of the salt salts of the solution with salts adsorbed by the ion exchanger.

However, if the size of the particles of the ion exchanger and the soil under study is different, i.e. due to their different water capacity, instrument readings will differ from actual conditions.

The aim of the invention is to increase the accuracy of soil moisture measurements, simultaneously determine their moisture capacity and concentration of salts dissolved in water, reducing the influence of ambient temperature and concentration of salts dissolved in water on the measurement results.

11el is achieved by the fact that in the sensor electrodes are arranged in pairs in an ion-exchange resin, on the outer surface

porous body and inside its walls, at the same time, the capacity of the latter is equal to the capacity of ion-exchange resin.

The presence of electrodes in three equal materials makes it possible to obtain reliable information about humidity.

, soil, their capacity and concentration of dissolved salts, due to the comparison of the readings of electrical conductivity of these materials. . ..

-; .-: -The drawing shows the principal

scheme of the proposed device. The sensor for determining the soil moisture has a housing 1 with porous walls, filled with an ion exchange resin. 2, equipped in pairs with a norbmen resin, on the outside of the body and in its porous wall with electrodes respectively 3, 4, 5. The sensor is placed in the soil under study 6.

The sensor works as follows, 15 With electrodes 3, 4, 5, connected to the measuring equipment 7, readings of the electrical conductivity of respectively ion-exchange resin 2, soil 6 and porous wall kbrpus 1.20 are taken

Moreover, due to the same moisture capacity, the humidity of the ion-exchange resin and. The porous wall of the hull is always the same. At the same time, the concentration of dissolved salts is different - in the ion exchange resin it is practically zero, the wall of the hull, due to ion diffusion, is equal to the concentration of dissolved salts of the soil studied.

The difference in the electrical conductivity of the zo-ion exchange resin and the porous wall of the body is caused only by the action of the dissolved salts, i.e. in the test soil.

Thus, we take readings that characterize the soil moisture, taking into account the influence of the concentration of dissolved salts from the measuring equipment connected to the electrodes 3, 4, 5 in a known manner.

The difference of indications obtained with elect 5 genera 4 and 5 is due to the different moisture capacity of the soil and the porous wall of the test. And since the moisture capacity is a more definite predetermined value.

then the magnitude of the difference in readings from electrodes 4 and 5, on the corresponding scale and; the measuring equipment will determine the data on the capacity of the soil under study.

Due to the fact that the temperature in all three materials, where electrical conductivity is measured, is the same, the effect of temperature is ignored on the difference in the readings obtained from the electrodes.

The presence of electrodes in the ion-exchange resin, on the outside of the porous core-, pus, and in its walls, whose moisture capacity is equal to that of the ion-exchange resin, provides more reliable information about the soil moisture, its moisture capacity and the concentration of dissolved salts, by comparing the electrical conductivity of these materials.

This allows you to more quickly and accurately respond to changes in living conditions.

plants, not tolerating a deficiency of moisture in soils or its overrun during irrigation. We propose a sensor to determine the soil moisture content gives more accurate readings, regardless of the type of soil, its capacity.

Claims (2)

1. Authors certificate of the USSR. No. 11289 2 ,. cl. COIN 27/12, 1957. 2. USSR author's certificate No. 195707, cl. GiOlN27 / 40, 1967 (prototype). ;